ISO 8292-1:2008 specifies a direct method for the determination of solid fat content in animal and vegetable fats and oils (hereafter designated "fats") using low-resolution pulsed nuclear magnetic resonance spectrometry. Two alternative thermal pre-treatments are specified: one for general purpose fats not exhibiting pronounced polymorphism and which stabilize mainly in the ß'-polymorph; and one for fats similar to cocoa butter which exhibit pronounced polymorphism and stabilize in the ß-polymorph. Additional thermal pre-treatments, which may be more suitable for specific purposes, are given in an informative annex. The direct method is easy to carry out and is reproducible, but is not as accurate as the indirect method due to the approximate method of calculation.
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Sisällysluettelo
Foreword
1 Scope
2 Normative references
3 Terms and definitions
4 Symbols and abbreviated terms
5 Principle
6 Apparatus
6.1 Pulsed nuclear magnetic resonance spectrometer, low resolution
6.2 Tubes
6.3 Temperature-maintenance equipment
6.4 Oven, with fan
6.5 Stop-clock
7 Sampling
8 Procedure
8.1 Measurement protocol and test sample
8.2 Oven, water baths and temperature-controlled blocks
8.3 Determination of the conversion factor (where necessary)
8.4 NMR spectrometer
8.5 Filling the measurement tubes
8.6 Removing the thermal history
8.7 Equilibrating at the initial temperature
8.8 Crystallization and tempering
8.9 Measuring the SFC
8.10 Number of determinations
8.11 Cleaning the measurement tubes
9 Expression of results
10 Precision
10.1 Interlaboratory test
10.2 Repeatability
10.3 Reproducibility
11 Test report
Annex A Results of interlaboratory tests (informative)
Annex B Theory of the direct method (informative)
Annex C Additional measurement protocols (informative)
ISO 661:2003 Animal and vegetable fats and oils -- Preparation of test sample
ISO 8292-2:2008 Animal and vegetable fats and oils -- Determination of solid fat content by pulsed NMR -- Part 2: Indirect method
ISO 661:2003 Animal and vegetable fats and oils -- Preparation of test sample
ISO 8292-2:2008 Animal and vegetable fats and oils -- Determination of solid fat content by pulsed NMR -- Part 2: Indirect method